"I really love getting to go into these places that I would just never be able to come up with on my own," she said. "So just to enter these worlds is so magical and it brings you back to being a kid where you could just have a complete fantastical world."

Going to Asgard means an entirely new, "amazing" and "beautiful" wardrobe for Portman, easily one of the perks of the job. "It's one of the joys of being in these movies, that there's just such a high level of craftsmanship," she said. "The silk is printed like specifically for the film, these Asgardian symbols and the jewelry and the armor is made by a metal worker in the studio and it's just like a level of craftsmanship of old movie making that we don't get to see much anymore."

Another new opportunity Portman seized in "The Dark World": working with Anthony Hopkins as Odin, the ruler of Asgard and father of Thor. "It was so crazy," she said of working with the veteran actor. "I was very intimidated, but luckily he's one of the kindest people I have ever met. So he made me feel really at ease and he's just, man, he's the best. You just sit there and try to remind yourself to act because he's just like, you are jaw dropped on the floor watching him."

There's no telling whether we'll see Jane Foster again after "The Dark World," but there's at least one place Portman doesn't expect to turn up: the "Avengers" arena.

"I don't think I would fit in very well," she said about a possible "Age of Ultron" appearance. "They haven't asked me, so we will see."